- Shot Peened Why do others substutute other inferior/untested steels? To decrease the cost of the part. Carpenter 158 is a high technology steel that is very expensive and can only be ordered in 20,000 lb mill runs. It is the only steel allowed by the US (and Foreign) Militarys for the very demanding needs of this high stress, critical part.

*BARRELS & BOLTS MUST BE PROPERLY CHECKED FOR HEADSPACE PRIOR TO USE. FAILURE TO DO SO MAY RESULT IN FIREARM DAMAGE, PERSONAL INJURY, OR DEATH*